@Article{Malejki2010, author = "Malejki, Maria", title = "Asymptotic behaviour and approximation of eigenvalues for unbounded block Jacobi matrices", journal = "Opuscula Math.", year = "2010", volume = "30", number = "3", pages = "311--330", doi = "http://dx.doi.org/10.7494/OpMath.2010.30.3.311", url = "http://dx.doi.org/10.7494/OpMath.2010.30.3.311", abstract = "The research included in the paper concerns a class of symmetric block Jacobi matrices. The problem of the approximation of eigenvalues for a class of a self-adjoint unbounded operators is considered. We estimate the joint error of approximation for the eigenvalues, numbered from \(1\) to \(N\), for a Jacobi matrix \(J\) by the eigenvalues of the finite submatrix \(J_n\) of order \(pn \times pn\), where \(N = \max \{k \in \mathbb{N}: k \leq rpn\}\) and \(r \in (0,1)\) is suitably chosen. We apply this result to obtain the asymptotics of the eigenvalues of \(J\) in the case \(p=3\).", keywords = "symmetric unbounded Jacobi matrix, block Jacobi matrix, tridiagonal matrix, point spectrum, eigenvalue, asymptotics", issn = "1232-9274" }